1. Field of the Disclosure
The disclosure relates to fire fighting in general, and, specifically, to a fire-extinguishing aerosol applicable in closed spaces.
2. Description of the Related Art
Fire-extinguishing aerosol is often generated as a by-product of combustion of specifically formulated substances containing potassium nitrates and/or perchlorates as an oxidizer and supplier of the main fire-extinguishing agent. As a binding fuel it uses plasticized and non-plasticized polymers, capable of transitioning to viscous or flexible state under the influence of thermal or/and mechanical nature. Among well known and widely used binding fuels, phenol-formaldehyde and epoxy resins, polyvinyl butyral, cellulose ethers, rubber are worth mentioning.
The main component of the fire extinguishing aerosol is super fine (0.5 to 5 m) particles of potassium compound formed by the chemical reaction between oxidizer and fuel and dispersed by the gaseous reaction products.
Fire extinguishing effectiveness of such aerosol is dependent on quantity and individual size of potassium compound particles, which itself depends on temperature and degree of completion of chemical reactions between oxidizer and fuel. In turn, combustion temperature of the composition directly depends on temperature of binding fuel combustion. D. I. Mendeleev formulated a calculation of estimated heat of combustion for solid and liquid fuels as:Q=81C+300H−26(O—S)−6(9H+W),
Where C, H, O, S and W—in the working mass of the fuel, are the presence of carbon, hydrogen, oxygen, sulfur, with moisture expressed in percentage of the mass and heat expressed in kcal/kg.
Results of the calculations for the heat of combustion for the variety of fuels and binding fuels are shown in FIG. 1.
The heat of combustion of the binding fuel determines the temperature of the produced aerosol. Practically, the value cannot exceed several critical points that determine the fire extinguisher's safety within the environment.
To lower the temperature of the fire extinguishing aerosol, existing methods add fire extinguishing cooling components such as ditsiandiamid, melema, melamine and others (patent RU 2095104, C1, 10.11.97), and/or utilize (in manufacture of the fire extinguishing aerosol generator) special cooling elements in the form of granules, tubes, monoblocks, or other components. (patent RU 2064305, C1, 27.07.96). Both methods reduce fire-extinguishing effectiveness of the aerosol by half or more compared to un-cooled aerosol, while increasing toxic products of the produced aerosol due to the increase in carbon monoxide, which does not oxidize in the air.
A significant development is an aerosol producing compound for fire fighting (patent RU 2160619, class A62D 1/06, from 20.12.2000), containing potassium nitrate 65-75%, binding fuel 0-5%, ditsiandiamid 10-20% and additional fuel that makes up the remainder of percentage, capable of burning along with potassium nitrate. In short, traditional binding fuel (phenol-formaldehyde resins or iditol) is replaced with another fuel (starch, hydroquinone, phenolphthalein, salicylic acid amide or similar) presumably to combat super heated particles. This method, in addition to producing high temperature aerosol, is limited in use.
In another known composition and production method thereof, the oxidizer undergoes dangerous and labor-intensive comminution wherein binding fuel is dissolved in the toxic methylene chloride to ensure even distribution components in the mixture (patent RU 2185865, class A62D 1/00, 27.07.2002).
Another closely related production method involves mixing components in 30-35% aqueous dispersion of polyvinyl (patent RU 2005517, class A62D 1/00, 15.01.94), but in this case, the oxidizer is insufficiently comminuted and persists in suspension in water.
Thus, what is called for is a solution addressing the described limitations.